Electric power systems may include power transmission and distribution networks and substations for transforming voltages and for switching connections between lines of the networks. Power generation and load flow within a power system may be monitored and/or managed by a Supervisory Control and Data Acquisition System (SCADA) and/or an Energy Management System (EMS).
State estimation may be used to provide real-time power flow status and modeling representations of a system, such as an electric power system or other system or network that has the characteristics of an electric power system, such as for use in or with an EMS, a Distribution Management System (DMS), or the like. State estimation provides the system operator with a system state for situational awareness and input to other applications, such as contingency analysis or voltage stability analysis. When used with an EMS, state estimators provide a state estimation for an electric power system based on a model of the power system and measurements from the field.
State estimators provide a state estimation based on static and dynamic data regarding the system. Static data may include a nominal topological model or a topology of the network, the types and placements of measurements, and the sign of the measured values. Dynamic data may include measurement values, open/closed statuses of circuit breakers (or other types of switches in the field) and indication signals.
The network topology may include the way transmission lines are connected to form the network, as well as the open/closed statuses of switches in transmission system substations. The way transmission lines are connected to form the network may define a static topology because the transmission line connections remain unchanged during the system operation. The circuit breaker and switch statuses in transmission system substations may define a dynamic topology because the breaker and switch statuses can change on the fly during the system operation.
Mistakes or errors in either the static or dynamic data may result in bias in the estimated system state, produce an incorrect solution, or result in non-convergence of the estimated state. For example, an incorrectly assumed topology in the model can have an adverse effect on the state estimation solution quality because the network connectivity or topology of the power system plays a role in defining the system model. Thus, any errors in the static or dynamic topology description, as assumed in the EMS database, may result in topology errors.
Errors in the dynamic data may include errors in analog measurements and errors in the dynamic topology due to incorrectly assumed open/closed statuses of circuit breakers and/or switches. Errors in the static data may include incorrect parameters or data, as well as an incorrect static topology. Incorrect static topology may include erroneous assumptions with respect to transmission line connections, the types or placements of measurements, or the signs of the measured values.
Examples of state estimation are disclosed in EP1783499 and U.S. Pat. No. 7,069,159. Further details regarding power system state estimation are explained in the textbooks entitled “Power System State Estimation: Theory and Implementation,” by A. Abur and A. G. Expósito (Marcel Dekker, New York, 2004) and “State Estimation in Electric Power Systems: A Generalized Approach,” by A. Monticelli (Kluwer Academic Publishers, Boston, 1999). The disclosures of these and all other publications referenced herein are incorporated by reference in their entirety for all purposes.